Pattern Polymorphism and Predation in the Shore Crab, Carcinus Maenas (L.)

Abstract

consumption of only 0.12 ml Oo/g/hr. compared to the smallest animal (1.84 g) which had a mean oxygen consumption of 0.49 ml 02/g/hr. The unit rate of metabolism, the theoretical metabolic rate when body weight is 1 g, for Coenobita is 0.70 ml 02/g/hr. at 24? C. This is relatively large when compared to a fully aquatic crustacean such as Procambarus alleni which has a unit metabolic rate of only 0.115 ml 02/g/hr. at 25? C. Uca, a littoral crab, has a higher unit oxygen consumption of 0.019-0.217 ml 02/g/hr. at 24? C, while Talitrus, a littoral amphipod, has a unit oxygen consumption of 0.533 ml 02/g/hr. at 25? C (Wolve kamp & Waterman, 1961). The data acquired in the present study for Coenobita, one of the most terrestrial species of Decapoda, support observations by previous workers that terrestrial Crustacea exhibit higher unit oxygen consumption than more aquatic species. Edney (1961) suggests that the ready availability of oxygen and the low density of air permit rapid and prolonged locomotion and subsequent elevated oxygen consumption in terrestrial species. However, higher rates of oxygen consumption in terrestrial species may also be a reflection of the increased energy required to cary the mass of the animal in a less buoyant medium.